Nomenclature: Coates Pal grave (1977).
Tree growth in an African woodland savanna affected by disturbance
Article first published online: 24 FEB 2009
2006 IAVS - the International Association of Vegetation Science
Journal of Vegetation Science
Volume 17, Issue 3, pages 369–378, June 2006
How to Cite
Holdo, R.M. (2006), Tree growth in an African woodland savanna affected by disturbance. Journal of Vegetation Science, 17: 369–378. doi: 10.1111/j.1654-1103.2006.tb02457.x
Department of Zoology, University of Florida, PO Box 118525, Gainesville, FL 32611-8525, USA; E-mail firstname.lastname@example.org; Fax +1 352 392 3704
- Issue published online: 24 FEB 2009
- Article first published online: 24 FEB 2009
- Received 4 May 2005; Accepted 8 March 2006.
- Kalahari sand;
- Savanna dynamics Stochastic rainfall;
- Tree architecture;
Questions: How does tree growth in a tropical woodland savanna vary as a function of size, and how is it affected by competition from neighbours, site attributes, and damage caused by disturbance?
Location: western Zimbabwe.
Methods: Trees of common species were tagged, mapped, and measured annually between 2001 and 2003 in a Kalahari sand woodland savanna. Diameter increments were analysed with mixed model regressions for the largest ramet in each genet. Stem diameter and damage, soil texture, and indices of competition at multiple spatial scales were used as covariates.
Results: Stem diameter increased initially and then declined as a function of size in undamaged trees, which grew faster than damaged trees. Growth in damaged trees declined with size. No site differences were detected, and there was evidence for between-tree competition on growth only in the fastest-growing species, Brachystegia spiciformis. In several species the growth rate of the largest ramet increased as a function of the basal area of secondary ramets, contrary to expectations. For many species, the growth models showed poor explanatory power.
Conclusions: Growth in Kalahari sand savanna trees varies as a function of size and changes in tree architecture caused by disturbance agents such as fire, frost, and elephant browsing. Disturbance may thus play an important role on vegetation dynamics through its effects on growth in the post-disturbance phase. Growth is highly stochastic for some species in this system, and more deterministic in others. It is hypothesized that this dichotomy may be driven by differences in rooting depth among species.